Clinton and her husband, hedge fund manager Marc Mezvinsky, have a daughter, Charlotte, who was born in 2014.

The new baby arrives as Hillary Clinton is hot on the presidential campaign trail. She has secured enough pledged delegates and superdelegates to become the presumptive Democratic nominee.

"We are overjoyed to be grandparents again with the arrival of our grandson, Aidan Clinton Mezvinsky, born on Saturday, June 18, 2016," Hillary and Bill Clinton said in a statement. "We are all over the moon as Chelsea and Marc welcome Charlotte’s little brother to the world and grateful for our many blessings. Chelsea and Aidan are both doing well and enjoying this very special time together."